The embodiments to a communication system, a computer and a method for determining a communication protocol to be used in the communication system. The embodiments further relates to a computer program product that can be loaded directly into the internal memory of a digital computer as well as to a computer program product that is stored on a computer-compatible and readable medium.
IPv6, Internet Protocol Version 6, is the successor to Version 4 of the Internet Protocol (IPv4) which is currently still predominantly used on the Internet. Both protocols are standards for the network layer of the Open Source Initiative (OSI) reference model and govern the addressing and the routing of data packets through a communication network. IPv4 uses 32-bit addresses so that an address space of just over four billion IP addresses is available which can be used to address computers and other devices. In the early days of the Internet, when there were just a few networked computers that needed an IP address, this was considered to be more than adequate. However, many of the theoretical four billion IP addresses cannot in actual fact be used, since they are used for special tasks or belong to large subnetworks. As a result, in some parts of the world, especially in the IT growth market of Asia, there is currently a shortage of addresses, which requires various temporary solutions. Owing to the growth and the importance of the Internet, this could not remain a permanent state of affairs, so IPv6 was developed to remedy this problem. IPv6 provides an address space of 3.4·1038 addresses.
As an extension of the IPv6 standard, Mobile IP was integrated in the IPv6 protocol under the name of Mobile IPv6 (RFC3775). Mobile IP provides an efficient mechanism for the mobility of computers in a communication system such as the Internet, for example. With Mobile IP it is possible for mobile computers to change their access point to the Internet but nevertheless retain their (static) IP address. To ensure the retention of the fixed IP address, Mobile IP provides each terminal with two addresses: a primary address is a so-called “home address”, and a secondary address is referred to as a “care-of address” (COA). If the mobile computer leaves its so-called home network and registers in a foreign network, the latter assigns it a care-of address, which it notifies to the “home agent”, a special computer in its home network. During data traffic, the home agent then forwards incoming data packets to the care-of address, and thus on to the mobile computer. If, on the other hand, the mobile computer wishes to send data packets, it can usually send them without the detour via the home agent, since the normal IP routing mechanisms ensure that the data packet reaches the destination. Once the mobile computer returns to its home network, it deregisters from its home agent again, so that data packets sent to it are again ensured without a detour via the home agent.
The situation may now occur that the foreign network to which the mobile computer is being connected can communicate both according to the IPv4 protocol and according to the IPv6 protocol. In order to be able to establish communication with a target computer, the mobile computer is therefore forced to send data packets with identical payloads both according to the IPv4 protocol and according to the IPv6 protocol. This procedure creates a heavy workload for the mobile computer and in addition creates unnecessary data traffic in the communication system.